Not Applicable
Not Applicable
1. Field of the Invention
This invention pertains generally to the installation of underground cables, and more particularly to an apparatus for stripping the insulation and semiconducting sheathing from an underground cable in preparation for termination or splicing of the cable.
2. Description of the Background Art
Conductive wires or cables typically have a central conductive core surrounded by one or more layers of insulation and an outer sheath. High voltage electrical cables typically have a semi-conductive outer sheath. Other cables may also have a second conductive layer separated from the conductive core by a layer of insulation. Stripping the end of the cable is necessary to allow an electrical or light energy connection with the cable.
Present wire or cable stripping tools known in the art range from simple hand tools to sophisticated motorized machinery. One type of prior art wire stripping tool is a plier like device with notches in the jaws which form a diamond shaped aperture when the jaws are fully closed. The wire to be stripped is placed in one notch and the jaws are closed cutting the insulation and allowing the conductive wire to be withdrawn through the aperture and the insulating sheathing removed thereby. However, the plier type wire strippers known in the art are unsuitable for stripping two levels of insulation or for stripping wires with a comparatively large cross-sectional areas.
Another common problem encountered with hand wire stripping tools is that the gripping and stripping of the insulation may cause damage to the conductor. The conductor may be cut completely or nicked thereby reducing the capability of the conductor to conduct current. The notched areas of the conductor may also create hot spots due to concentrations of current as well as weak spots that can result in breakage of the conductor. It has therefore become a practice to leave a small amount of insulation on the cable to be removed by hand so that the conductor is not exposed to or notched by the cutting blade. Care must also be taken when removing the semi-conductive sheathing from a high voltage cable not to cut the insulation layer or to imbed pieces of the sheathing into the insulation layer.
Other well known wire strippers have an elongate body with cutting blades which rotate about the exterior of the cable to remove the outer sheath of the cable. Such devices can be rotated by hand or rotated by an electric motor. One deficiency in these types of strippers with a permanently fixed blade is that the stripper cannot accommodate a range of cable insulation diameters. Another deficiency in the prior art hand actuated and motorized stripping devices is that the devices can not be efficiently used in confined spaces.
Accordingly, there is a need for a motorized cable stripping device which provides for removal of the sheathing layer of a portion of the cable without cutting the insulation while the end portion of the cable has the sheath and insulation layers removed to expose the conductive core, and which is easy to use and can be used in a confined space. The present invention satisfies those needs, as well as others, and generally overcomes the deficiencies found in the background art.
The present invention generally comprises a cable stripping tool with a cylindrical body having a central bore or hollow throughout its length that can receive the end of the cable to be stripped. The cylindrical body has a longitudinal slot and a laterally disposed discharge port which extends through the walls of body to the central bore. An insulation cutting blade is mounted in the discharge port extending into the central bore and configured so as to remove the sheathing and insulation layers of a cable. The discharge port is preferably positioned near the middle of the length of the device.
A scoring blade assembly is disposed above and in the longitudinal slot such that the tip of the scoring blade engages and rides the outer sheath of the cable when it is placed in the central bore. A spring maintains pressure on the scoring blade. An adjustable set screw maintains the depth of the score which does not fully penetrate the sheath. The blade assembly is preferably adjustable and can be positioned at any point along a raceway above the slot.
A shaft assembly is mounted opposite the cable receiving end of the elongate body and centered along the central axis of the generally cylindrical body.
In use, the cable is inserted into the opening in the open end of the body. A portable drill or other source of rotational power is attached to the shaft. When rotational power is applied to the apparatus, it rotates around the cable, thus stripping the sheath and insulator from a section of the cable with the insulation cutting blade and scoring the semiconducting layer of another section with the scoring blade. The scored sheath is then peeled by hand after scoring to avoid cutting the insulation layer.
It is an object of the invention to provide a novel means of preparing insulated cable having at least one insulation layer and a sheath for splicing or termination.
Another object of the invention is to provide a cable stripping device that can accommodate insulated cable with a comparatively wide diameter.
Yet another object of the invention is to provide a wire stripping device that is efficient, reliable and easy to use.
A further object of the invention is to provide a cable stripping device with cutting blades that can be adjusted to cut to a range of depths.
Another object of the invention is to provide a cable preparation device that can be readily utilized in confined spaces.
Yet another object of the invention is to provide a cable stripping device which is rugged and simple to fabricate.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.